Schedules that Make Sense

This is the school schedule. When I first arrived at site, I tried very hard to make sense of it, thought it was like reading a code. On the right side is a list of the teacher's name and their corresponding numbers. I would think there must be more efficient and less cryptic ways to create a high school schedule. Although, when students are taking 14 classes per year, things tend to look like this. Indonesia, July 2011.